An optical module that enters a laser beam, which is emitted from a semiconductor laser element, to core of an optical fiber is known. In this optical module, generally, a laser sub-mount and a fiber mount are disposed on a base, relative positions of end portions of the semiconductor laser element and the optical fiber exactly correspond to each other, the semiconductor laser element is fixed on the laser sub-mount, and the optical fiber is fixed on the fiber mount.
The optical fiber is generally fixed to a bonding pad, which is formed on the upper surface of the fiber mount, by solder. This solder is usually melted by heat, which is caused by a laser beam, at the time of soldering. However, for the prevention of the modification, such as oxidation, of solder, the solder is not directly irradiated with a laser beam and the fiber mount is irradiated with a laser beam. As a result, the solder is melted through the conduction of heat from the heated fiber mount.
Incidentally, ceramic may be used for the fiber mount in terms of heat resistance and the like. However, some kinds of ceramic, which can be used for the fiber mount, transmit a laser beam that is used for heating. For this reason, there is a case in which it is difficult to heat the fiber mount by a laser beam as described above. Accordingly, in an optical module disclosed in the following Patent Document 1, a laser absorption layer, which is made of titanium, absorbs a laser beam, and converts the laser beam into heat, is provided on a fiber mount. However, since this laser absorption layer has low thermal conductivity, a large thermal gradient is generated on the surface of a bonding pad that is positioned on the same plane. When a thermal gradient on the surface of the bonding pad is large as described above, a portion having good solder wettability and a portion having poor solder wettability are formed on the bonding pad, so that the position of an optical fiber is shifted at the time of solidification of the solder. For this reason, there is a concern that the characteristics of the optical module have a variation. Accordingly, in the following Patent Document 1, a heat conductive layer made of nickel is provided in addition to the laser absorption layer so that heat generated in the laser absorption layer is conducted to the entire bonding pad.    [Patent Document 1] U.S. Pat. No. 6,758,610